Case III
Letter
Mass
% Error
D
270.5g
-.00192
B
256.75g
-.00295
R
132g
-.00302
E
205.5g
-.0031
F
197.25
.0028

Case IV
25.2 cm=new equilibrium
100 g
50 cm=original equilibrium

m(of ruler)*24.8=100*20.2
m(of ruler)=81.45 g
Didn't find the actual mass of the meter stick for unknown reasons.
Questions
1) forces and torque?
A large force can produce little torque if the force is applied right at the center.
A small froce can produce large torque if the force is applied far away from the center.

2) "support force" not included?
The "support force" is not included into our torque calculations directly because it cancels with the vertical forces.

3) 10*?+120*50=220*35
?=.1283333333 g